Elastic rotary coupling, particularly for the driving of rpm regulators associated with fuel injection pumps

ABSTRACT

In an elastic rotary coupling for the transmission of torque there is provided a shaft-like driving component coaxially surrounded by a sleeve-like driven component. Aligned recesses in the two components form a plurality of nests each accommodating an elastic (for example, rubber) coupling element. The cross section of each elastic coupling element has the general shape of a rectangle with rounded corners and depressed sides. In the position of rest the elastic coupling element only partially fills the space defined by the nest.

United States Patent [191 Eheim July 2, 1974 ELASTIC ROTARY COUPLING, 2,993,544 7/1961 Carlson 64/27 R PARTICULARLY O THE DRIVING OF 3,687,479 8/1972 Kober 267/57.l

RPM REGULATORS ASSOCIATED WITH FUEL INJECTION PUMPS Franz Eheim, Stuttgart, Germany Robert Bosch Gmbll, Stuttgart, Germany Filed: Jan. EH, 1973 Appl. No.: 328,441

Inventor:

Assignee:

Foreign Application Priority Data Mar. 17, 1972 Germany 2212913 References Cited UNITED STATES PATENTS l [/1960 Selzer 64/27 NM Primary Examiner-Samuel Scott Assistant Examiner-Randall Heald Attorney, Agent, or Firm-Edwin E. Greigg ABSTRACT In an elastic rotary coupling for the transmission of torque there is provided a shaft-like driving component coaxially surrounded by a sleeve-like driven component. Aligned recesses in the two components form a plurality of nests each accommodating an elastic (for example, rubber) coupling element. The cross section of each elastic coupling element has the general shape of a rectangle with rounded corners and depressed sides. In the position of rest the elastic coupling element only partially fills the space defined by the nest.

3 Claims, 2 Drawing Figures ELASTIC ROTARY COUPLING, PARTICULARLY FOR THE DRIVING OF RPM REGULATORS ASSOCIATED WITH FUEL INJECTION PUMPS This invention relates to an elastic rotary coupling, particularly for driving rpm regulators associated with internal combustion engines and is of the type which has coaxially arranged driving and driven components interconnected by means of elastic elements. The latter are disposed in cavities or nests formed by aligned recesses which are provided in the driven and driving components and which have a constant cross section at any point along an axially parallel direction.

A known coupling of the aforenoted type comprises two coaxially arranged components and, for the transmission of torque, elliptically shaped elastic members which are disposed in ellipsoid-shaped cavities, each formed of a pair of aligned recesses provided in the coaxial components. Each elastic member entirely fills the cavity in which it is disposed. There are known other couplings in which between the driven and the driving components there are disposed cylindrical elastic elements.

Couplings of the aforeoutlined type have the purpose to take up in a small space as large forces as possible in such a manner that shocks or impacts generated at the driving side are not transmitted to the driven side. In this manner it is sought to protect the driven side from rapid wear or destruction. It is a further purpose of these couplings to compensate for alignment errors in a simple manner and to dampen oscillations that may appear at the driving side.

It is an object of the invention to provide an improved drive means for an rpm regulator particularly of the type used in fuel injection pumps which transmits the aforeoutlined nonuniformities to the rpm regulator only partially, if at all. Particularly sudden sub stantial rpm changes are to be transmitted to the regulator in a dampened manner.

Briefly stated, according to the invention, the elastic coupling elements have a cross-sectional shape of a rectangle, the long sides of which extend substantially tangentially to the direction of rotation. Said rectangle has rounded corners and a depression on each side. Each cavity or nest provided in the coupling components for receiving an elastic coupling element has a greater cross-sectional area than that of the elastic element, so that the latter does not entirely fill the space defined by the nest when the coupling does not rotate. The driven component has in its lateral face adjoining the driving component an additional cavity which has a cross section in the shape of an annular sector. A coupling pin affixed to the driving member projects into the last named cavity and is freely movable therein as a function of the deformation of the elastic elements. It is to be noted that in the particular intended use the torques transmitted by the coupling may remain relatively small, as opposed to the aboveoutlined known structures that are generally used in an environment where the transmission of relatively large torques is necessary.

The invention will be better understood as well as further objects and advantages become more apparent from the ensuing detailed specification of a preferred, although exemplary embodiment taken in conjunction with the drawing wherein:

FIG. 1 is a side elevational, partially axially sectional view of a coupling incorporating the invention and FIG. 2 is a sectional view along line IIII of FIG. 1.

Turning now to FIGS. 1 and 2, in a fuel injection pump housing 1 there is rotatably supported a driving component 2 formed as a drive shaft surrounded coaxially by a sleeve-like driven component 3-which, at its outer circumference, is provided with a gear 4 meshing with a spur gear 5 of an rpm regulator 6. The driven component 3 includes at its inner lateral face two recesses 7 having a dish-shaped cross section. With each recess 7 there is aligned a recess 8 which has an outwardly concave cross section and which is provided in the outer lateral face of the drive shaft 2. Each aligned recess pair 7, 8 defines a nest which accommodates an elastic couplingelement 9. As it may be well observed in FIG. 2, the cross section of each elastic coupling element 9 has the approximate shape of an elongated rectangle, the length dimension of which extends generally tangentially to the direction of rotation of the coupling components 2 and 3. The corners of the cross-sectional rectangle are rounded and its sides slightly depressed. When the coupling components are not rotating and thus each elastic element 9 is stressfree, the latter fills only partially the space defined by the nest 7, 8.

The driven component 3 has at its lateral face adjoining the driving component 2 a cavity 10 having a crosssectional shape of an annular sector. To the driving component 2 there is fixedly attached a coupling pin 1 l which extends outwardly from the circumferential face of the driving component 2 and projects into the cavity 10. The pin 11 is freely movable between the two side walls of the cavity 10; the exact position of the pin 11 is determined by the extent of deformation of the elastic elements 9. During normal operation the driving pin 11 is out of contact with either side wall of the cavity 10. In the unlikely event of a failure of the elastic ele-- ments 9 the coupling pin 11 arrives into an abutting engagement with the lateral wall of the cavity 10 and thus the driven component 3 continues to be rotated by the driving component 2. Such a continued driving connection despite a failure of the elastic couplingelements is of particular importance in regulators associated with fuel injection pumps.

The aforedescribed novel structure has the advantage that the elastic elements are first of all exposed along their longitudinal and diagonal axes to compression and then to shearing stresses. By shaping the elastic elements in the aforeoutlined manner there is achieved a soft coupling engagement, since first the small cross-sectional parts of the elastic element are exposed to compression. Then, under continuing load, the elastic coupling element may deform into the initially available spaces between the elastic element and the cavity and only lastly is the entire cross section of the element exposed to compression and then to shearing stresses. By virtue of the combination of the particularly shaped recesses 7 and 8, theelastic coupling ele ments 9 are first diagonally compressed as the relative movement between components 2 and 3 begins as the shaft 2 starts to rotate. In this manner a soft coupling engagement is ensured. Furthermore, the outwardly concave configuration of the cross section of the recess 8 maybe provided in a simple manner by a milling operation.

What is claimed is:

1. An elastic rotary soft coupling arrangement comprising A. a driving component;

B. a driven component disposed coaxially with respect to said driving component,

C. recesses provided in said driving and driven components, at least one recess in said driving component and at least one recess in said driven component forming an aligned pair and constituting a nest,

D. an elastic coupling element received in said nest and occupying, when in stress-free condition as a result of not rotating, one part of the volume enclosed by said nest, said elastic coupling element having a cross section in the approximate shape of an elongate rectangle having a length dimension oriented approximately tangentially to the direction of rotation of said coupling, said rectangle having rounded corners and slightly depressed sides, and said elastic coupling element being exposed along its longitudinal axis and its diagonal axis to compression and then shearing stresses upon rotation thereof, the small cross-sectional portions of said elastic coupling element being firstly subjected to compression,

E. a cavity provided in a face of said driven component adjoining said driving component, said cavity having side walls and I F. a coupling lug affixed to said driving member and extending into said cavity, said coupling lug being out of contact with either side wall during normal operation, the position of said coupling lug between said side walls being freely changeable as a function of the deformation of said elastic coupling element.

2. An elastic rotary coupling as defined in claim 1, wherein said recesses in one of said components have an outwardly concave cross section and said recesses in the other of said components have a dish-shaped cross section.

3. An elastic rotary coupling as defined in claim 1, wherein said driving component being formed as a shaft, said coupling lug being constituted by a pin extending radially outwardly from said shaft. 

1. An elastic rotary soft coupling arrangement comprising A. a driving component; B. a driven component disposed coaxially with Respect to said driving component, C. recesses provided in said driving and driven components, at least one recess in said driving component and at least one recess in said driven component forming an aligned pair and constituting a nest, D. an elastic coupling element received in said nest and occupying, when in stress-free condition as a result of not rotating, one part of the volume enclosed by said nest, said elastic coupling element having a cross section in the approximate shape of an elongate rectangle having a length dimension oriented approximately tangentially to the direction of rotation of said coupling, said rectangle having rounded corners and slightly depressed sides, and said elastic coupling element being exposed along its longitudinal axis and its diagonal axis to compression and then shearing stresses upon rotation thereof, the small cross-sectional portions of said elastic coupling element being firstly subjected to compression, E. a cavity provided in a face of said driven component adjoining said driving component, said cavity having side walls and F. a coupling lug affixed to said driving member and extending into said cavity, said coupling lug being out of contact with either side wall during normal operation, the position of said coupling lug between said side walls being freely changeable as a function of the deformation of said elastic coupling element.
 2. An elastic rotary coupling as defined in claim 1, wherein said recesses in one of said components have an outwardly concave cross section and said recesses in the other of said components have a dish-shaped cross section.
 3. An elastic rotary coupling as defined in claim 1, wherein said driving component being formed as a shaft, said coupling lug being constituted by a pin extending radially outwardly from said shaft. 